The synthesis processes Of Si3N4 from the carbothermal reduction of SiO and SiO2, respectively, are studied. It has been concluded that the reaction temperature is lower if SiO instead of silica is used as raw material. The use of the Constant Rate Thermal Analysis (CRTA) method allows a silicon nitride to be obtained with an average crystallite size of 1 mum, a narrow size distribution, and a percentage of alpha-silicon nitride higher than 98%.